This invention relates to a rotary damper with a directional property, and more particularly to a rotary damper adapted to exert a turning force varied in magnitude depending upon the direction of rotation.
Recently, a rotary damper has been extensively used for, in particular, a cassette tape ejecting mechanism in a cassette tape recorder, a video tape recorder (VTR) or the like, because it allows a cassette holder actuating operation to be gracefully and smoothly carried out and effectively prevents the generation of an impact noise and a vibration. Particularly, even when a mechanism to be subjected to a damping operation exhibits a linear motion or a motion similar thereto, the rotary damper can readily convert such motion into a rotary motion. Thus, it is considered in the art that the rotary damper has a significant advantage over a linear damper.
One of conventional rotary dampers of such type is disclosed in Japanese Utility Model Application Laid-Open Publication No. 58-167351 (Japanese Patent Application No. 57-63842). The conventional rotary damper is constructed by providing a non-directional rotary damper with a one way clutch mechanism. However, it is apt to break down because of its complicated structure and the use of many parts. Also, the conventional rotary damper has another disadvantage that it is difficult to accomplish a precise and stable clutch operation because the angle of rotation required to actuate the one way clutch is 30 to 50 degree or more. There is known in the art another rotary damper which is constructed to utilize air resistance due to a gear and a windmill. However, the conventional damper is also apt to break down because it is complicated in structure and includes many parts. Also, a further conventional rotary damper is known which is adapted to carry out the actuation of a cassette holder utilizing a motor. However, it is increased in manufacturing cost, so that it is limited to the application to a high-grade apparatus.